Automatic safety curtain apparatus for air enclosing structures

ABSTRACT

A safety curtain apparatus for automatically blocking an air opening in an air pressurized structure has means to retain a safety curtain in retracted position and release it to block the opening when undesired relative movement sufficient to cause unblocking of the opening occurs between parts of the structure by utilizing a releasable support means to hold the curtain retracted adjacent the opening at a first portion of the structure and a curtain releasing means operatively connecting between the support means and another portion of the structure and operative to release the curtain to cover the opening whenever significant undesired relative movement occurs.

United States Patent Redden [54] AUTOMATIC SAFETY CURTAIN APPARATUS FOR AIR ENCLOSING STRUCTURES [72] Inventor: Robert J. Redden, Newark, Del.

[73] Assignee: [LC Industries, Inc., Dover, Del.

[22] Filed: June 8, 1970 [21] Appl. No.: 44,451

r [52] US. Cl ..l60/98, 5212, 135/14 D [51] Int. Cl ..E04b 1/345, A45f 1/00, E061) 5/00 [58] Field of Search 160/ 1-9, 98, 242-245; 135/4 D, 4 V; 52/2 [56] References Cited UNITED STATES PATENTS 3,006,352 10/1961 Hozak ..52/2 957,923 5/1910 Wilson ..160/1 3,478,472 11/1969 Kwake ..52/2

[451 Aug. 8, 1972 FOREIGN PATENTS OR APPLICATIONS 1,235,094 5/ 1960 France ..52/2

Primary Examiner-Peter M. Caun Att0rneyD0nald D. Demon ABSTRACT A safety curtain apparatus for automatically blocking an air opening in an air pressurized structure has means to retain a safety curtain in retracted position and release it to block the opening when undesired relative movement sufiicient to cause unblocking of the opening occurs between parts of the structure by utilizing a releasable support means to hold the curtain retracted adjacent the opening at a first portion of the structure and a curtain releasing means operatively connecting between the support means and another portion of the structure and operative to release the curtain to cover the opening whenever significant un desired relative movement occurs.

12 Clalns, 8 Drawing Figures PATENTEDMIF 81912 SHEET 1 (IF 2 INVENTOR.

ROBERT J. R EDDEN PATENTEDM 8:912 3.682.225 SHEEI 2 BF 2 i 1 INVENTOR 5 ROBERT J. REDDEN AUTOMATIC SAFETY CURTAIN APPARATUS FOR AIR ENCLOSING STRUCTURE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a safety device for effecting closure of an air passage or opening into a space enclosing structure that may become unblocked, in order to prevent unwanted movement of air through the opening. More particularly, the invention concerns a device which maintains a panel means ready to be released into blocking relation to an entranceway for personnel, materials or like opening in a building structure and then release the panel means so as to cover the opening whenever sufficient relative displacement occurs between one portion of the structure and another portion that would normally prevent interchange through the opening of air within the structure and the external ambient air surrounding it. The invention is highly suitable for use with inflatable-type structures, for example air supported building structures where an opening into the structure from the exterior, if unblocked, could allow escape of the necessary building support air which might cause deflation and collapse of the building structure.

2. Description of the Prior Art With the increased use of inflatable type building structures has come a need for auxiliary portions or components, such as small enclosures for equipment, entranceways for personnel or materials, or the like to form part of the building structure. Such auxiliary components often communicate with an opening in the main body of the structure and provide a closure over such opening that normally blocks unwanted passage of air therethrough between the building and the external environment. Where it is desired to form the auxiliary component so as to be easily detachable from the building structure, there has existed the possibility that the auxiliary component can become detached from the main body of the structure with resulting loss of necessary building inflating air. This can occur in the event of high winds, particularly if coupled with low air pressure within the structure which can occur, for example, in the event of reduced electrical power available to operate devices supplying building inflating air. Moreover, the use in such components of an entrance door of only the single panel type hinging at one side has not been favored due to the possibility that such a door may be left open, inadvertently or by vandalism, resulting in unblocking the opening into the main body of the structure from the exterior with consequent loss through the air passage thus formed of necessary building supporting air pressure. Resort, therefore, has sometimes been had to complicated air lock or door closing devices in attempts to provide security against loss of the necessary inflating air at portions of the building structure designed for personnel or materials to enter or leave.

Such expedients, however, in addition to being complex and expensive, can be difficult to transport or install which limits the use and mobility of inflatable type buildings. They have thus not provided the needed simplified safety apparatus securing against loss of building inflating air. They have also not provided an immediate automatic covering over of an air passage that may be opened into the structure whenever undesired blocking of an opening into the building structure occurs or when relative displacement takes place between the body of the structure and the body of an auxiliary component nor when it is desired to use the ordinary side hinging single panel type door as an entrance closure, particularly where the door opens outward.

This invention provides a much-needed simplified apparatus for effecting immediate automatic blocking of an opening or air passage into a building structure in response to a triggering disturbance of one portion of the structure with respect to another. in a particular embodiment, the present invention provides for holding and automatically releasing a panel means to cover over an air passage opened into an inflatable type building and prevent building collapse from loss of air pressure in the event that a closure means or auxiliary component becomes disconnected therefrom or when undesired opening of an access door communicating with the opening occurs which would permit escape of building inflating air. Such auxiliary component can be, for example, a chamber, framing, entranceway or other extension to the building structure. Accordingly, this invention contemplates safety apparatus for holding a panel or curtain means and releasing it to cover over a normally blocked air opening into a building structure, when undesired relative movement occurs between portions of the structure, which has support means for holding the panel means retracted adjacent the opening, and release means connecting between the support means and another portion of the structure and operative on occurrence of the undesired movement to effect release of the panel means to a position blocking the air opening into the structure. After its release the panel means is held against a surface of the building structure by air pressure so as to block the opening and seal it against any substantial flow of air therethrough.

Safety apparatus according to this invention can at once provide the necessary security against air interchange between the building structure surroundings and its interior due to unwanted relative displacement with respect to the main body of the building structure of either an auxiliary component to the structure and/or one or more normally movable parts thereof, for example, an entrance door. When the safety device is used with an inflatable type building the sealing of the opening is effective to prevent damaging loss of building inflating air.

The support means advantageously can be a cradlelike or sling-like device for containing the curtain out of the way near the opening to be covered and provided with releasable curtain retaining means that can be fastened or linked together so as normally to retain the curtain rolled up in the cradle. The curtain thus can be held in its non air blocking or retracted position until occurrence of unwanted relative movement between portions of the building triggers release or opening of the retaining means causing the curtain to be released so as to drop over the opening and close it against unwanted flow of air.

Advantageously, the means for releasing the curtain may be formed as a harness having connecting or motional stress transmitting means interconnected with the curtain support means and a normally non-movable portion of the building, such as framework of an auxiliary component thereof, which provides for the curtain to cover the opening by transmitting the undesired movement or displacement between building portions or components to the curtain support means. The curtain releasing means advantageously can also have a further connecting or motional stress transmitting means optionally attachable to a portion of the building that is normally movable, such as an entrance or access door positioned in an operationally non-moving auxiliary component that is attachable to the building as a part of the complete building structure. With this construction the first connecting means can be attached to the body or frame of the component to sense the undesired motion or displacement and effect release of the curtain if the component should separate from the main body of the building structure. In addition, or alternatively, the second connecting means can be connected to the operationally movable access door whenever desired so that unwanted movement of the door will be sensed thereby and cause the connecting means to effect release of the curtain from its support means and allow the curtain to drop and close off its associated opening.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the invention will become more apparent from attention to the annexed drawings and description making reference to preferred embodiments of the invention presented as only illustrative and not as limitative of the inventive concepts herein and in which:

FIG. I is a perspective view of an inflatable type building structure having the apparatus of this invention installed therein and showing an attached auxiliary component providing a passageway or entranceway into the building and a single panel entrance door in the outer opening thereof with the position of the curtain when rolled up indicated in broken lines;

FIG. 2 is a fragmentary cross-sectional view in elevation taken along line 22 of FIG. 1 showing the safety curtain held retracted above the opening defined through the building and the passageway, and ready to be released, and in broken lines the position of the curtain after release blocking over the opening into the main body of the building;

FIG. 3 is an elevational view from within the building of the apparatus as seen along line 3-3 of FIG. 2, with the position of the curtain when retracted as a roll in solid lines, and in broken lines the position of the curtain when in its released position fully covering over the opening;

FIG. 4 is a schematic plan view showing the arrangement of the breakaway straps or curtain holding and releasing device in the ready position of FIG. 2 with respect to the auxiliary component and the safety curtain;

FIG. 5 is a fragmentary perspective view from within the building of one end portion of the coiled or retracted curtain showing how it is held by one of the slings in the support cradle formed by the breakaway straps;

FIG. 6 is a view similar to FIG. 5 showing the inner and outer retaining means of the support cradle disconnected to open it and the curtain released and dropping over the opening;

FIG. 7 is an elevational view similar to FIG. 2 showing the auxiliary component broken away from the extension of the building structure by reduced inflation in the building main chamber and the curtain dropping when released thereby; and

FIG. 8 is an elevational view similar to FIG. 7 showing how unwanted opening of the access door triggers release and dropping of the safety curtain.

DESCRIPTION Referring to the drawings, an automatically actuated safety curtain device or apparatus in accordance with this invention is indicated generally at 20 and includes a panel means or safety curtain 22 and a novel curtain holding and releasing device 24. The apparatus is shown installed in an inflatable type building structure or building 26 that has associated with it equipment (not shown) for air-inflating the building as may be desired. The inflating equipment may be connected to an outside source of electric power with self-contained equipment available in emergency to maintain full or reduced inflation of the building. The building has a main chamber or body bounded by a wall 28 of gas impervious flexible material such as treated fabric, plastic sheet material, or the like, with an air passage or opening 30 large enough for a person to walk through defined through the wall at one side of the structure.

Secured to the wall is a short tunnel-like wall extension 32 constructed of like flexible material to that of wall 28 and which surrounds the opening 30 externally thereof so as to form an antechamber 33 making up part of the complete building structure. At the outwardly directed end of the antechamber the wall extension is blocked by a closure or auxiliary component 34 which is a separate module releasably connected to the extension, for example, by a cable clamp, so as also to form part of the building structure.

The auxiliary component includes a base 36 that can be anchored to the ground or other underlying support surface for the building and an upstanding rectangular frame 38 supported on the base and defining an entrance in which there is a manually operable access or entrance door 40 to provide the component with an openable closure means. It can be seen that the auxiliary component need be only of a width to just accomodate the door which is of the ordinary single panel type and supported on hinges 42 positioned in one side of the frame for pivotal swinging out or in in the usual manner. The door is provided with a doorknob on the outer side and a push bar 44 on its inner side which, when manipulated, can operate a releasable door latch (not shown) to provide for manual unlatching and opening of the door or latching of it closed in a substantially air tight position. Door 40 opens outward and gaskets can be used for air sealing. The auxiliary component thus forms an entranceway for personnel or materials to pass through the antechamber 33 and the opening 30 into or out of the main body of building 26. It will be appreciated that when the building is inflated, opening of the door permits air to flow out of the structure through the opening 30 but in the operative condition of the building the door is nonnally latched closed which blocks any substantial exchange of air between the interior of the building and the exterior or ambient air that surrounds the structure.

The safety curtain 22 is provided against emergency to cover over and block the opening 30 against outflow of air from within the building in event unwanted unblocking of the opening occurs. The curtain, which is generally rectangular, is positioned within the main portion or body of the building and normally held or cradled up out of the way above the opening during normal building use as a horizontal curtain roll by the holding and releasing device 24. The curtain has a top or upper edge 46 by which it is attached to wall 28 above opening 30 so that when attached and rolled up into device 24 it is suspended from its upper edge in retracted position lying close along the inner surface of the building wall.

Curtain 22 itself is a flexible panel formed of a thin, lightweight and generally flat fabric-like sheet of gas impervious material which can be easily rolled up then unrolled when released from its support in device 24. Material similar to that used for the building wall has been found suitable but may be somewhat lighter in weight. The curtain is slightly larger in height and width dimension than the opening 30 so when in its extended or released position in which it covers over and blocks the opening 30, its marginal edges or border areas can seal against the corresponding wall portions of the building that form the surrounding margins or periphery of the opening. Attachment of the curtain upper edge 46 to the inner surface of wall 28 is accomplished by sewing but the curtain can be made entirely removable from the building by using releasable attachment means such as snap fasteners to join its upper edge to the wall. Also, curtain 22 is provided with transverse stiffening means in the form of a series of stiffening rods 48 arranged horizontally across the width of the curtain and spaced apart vertically at intervals along the height dimension of the curtain when it is extended. The rods are positioned in the curtain so the marginal edges of its outer-directed face, when in unrolled or extended condition can lie against the wall 28 around the periphery of the opening so as to seal against it. The vertical flexibility together with the transverse rigidity and in some cases the added weight given by the rods to the curtain provides for an even and orderly unrolling of it over the opening after release and then assists it to have a secure progressive holding and sealing of its marginal edges against the inner wall surfaces bordering the periphery of the opening as air pressure within the building presses the curtain outward (See esp. FIG. 3).

For supporting or maintaining the curtain 22 in its normally retracted position and releasing it in emergency, the curtain holding and releasing device 24 has a cradle device or cradle 50 which fonns a support means for the rolled up curtain and also has a curtain releasing means or harness 52 which can be actuated to open or release the cradle and allow the curtain to unroll or drop to its air-flow blocking position covering over the opening 30.

The harness provides means for transmitting to the cradle, so as to open it, stress from the undesired relative motion between portions of the structure by utilizing a pair of curtain main release straps 54, 540, which make up part of cradle 50, and by a Y-strap link 56 forming a curtain auxiliary release means. As can be seen, the straps and strap link respectively provide for the harness to be operatively connected between the cradle and the frame 38 or optionally to door 40 or to both, so as to individually sense and respond to relative movement between one or more of the latter parts and the main body of the building, and thus trigger operation of the apparatus by tensioning the harness if the parts move apart to open the cradle and drop the curtain.

Cradle 50 is constructed with a first or inner retaining means, or curtain support member of a pair of generally vertically arranged curtain roll support tapes 62, 620, each of which has its upper end attached to the inner surface of the building wall above the upper edge of the curtain. The tapes are positioned in the building wall by sewing, but can be separately attachable thereto by fastener devices such as snaps or the like and are extendable over the inner-directed face of the curtain near opposite side edges thereof. The cradle also has a second or outer support or, retaining member of a pair of curtain roll supporting stirrup strips 64, 640, each generally vertically arranged and attached at its upper end to the inner surface of the building wall below the curtain upper edge. The strips depend over the outer face of the curtain and are aligned with a respective opposite support tape 62 or 62a so that at each opposite end of the curtain roll one of the support tapes and its counter part stirrup strip forms, when linked together at their lower ends, an openable slinglike curtain supporting loop or ring. The rings, when completed by the straps 54, 54a, combine to form the cradle as a bottom openable or releasable sling which supports the curtain in its unextended or retracted position rolled up at the opening 30 when the apparatus is placed in operation.

For attaching together the tapes and strips so as to loop under or ring about the ends of the curtain roll each stirrup strip terminates in a respective stirrup 66, 660 which can slidably receive through it one of the main release straps 54, 540 that respectively complete the flexible rings making up the cradle. In addition, the free ends of each of the support tapes are provided with snap fastener first elements 68, 68a of a pair of releasable disconnects 70, 70a. A mating snap fastener second element '72, 72a of each disconnect is attached to a respective inner-directed end of one of the harness main release straps 54, 540. As apparent in the drawings, disconnects 70, 70a provide the cradle with the necessary easily releasable connection means for holding the outer and inner members of the cradle frictionally closed and linked together by the harness under the rolled up curtain to support it in roll form or when the elements of the disconnect are separated by pulling action of the harness to release the curtain to fall over the opening 30. As both the support tapes and stirrup strips are made of strap-like flexible webbing, the holding and releasing device 24 is fully flexible which makes for easy handling and installing and accommodates for variance in the tightness with which the curtain is rolled up to retracted position.

It can be seen that the main releasing straps 54, 540 are together first release means for the curtain adapted to form a primary safety connection or connecting means operatively linking the cradle disconnects directly with the auxiliary component 34 by attachment to frame 38. Similarly the Y-strap link 56 is a second curtain release means which by connection to the straps 54, 540 forms a secondary safety connection or connecting means adapted to operatively link the cradle disconnects with the door 40 whenever desirable (see esp. FIG. 4).

The main release straps 54, 54a, each have at their outer-directed ends one part of a pair of securement means 76, 76a that have their other parts respectively permanently affixed to the upper crosshead of frame 38 at outer side edges of the auxiliary component. The parts of these securement means are securely joined together when the apparatus is in use. Thus any substantial unwanted relative movement occurring between the body or frame of component 34 and the main body of the building will be communicated through the main release straps to the disconnects 70, 70a unsnapping them to open the cradle and release the curtain. To take up slack and hold the straps of the harness 52 up out of the way at the ceiling of the extension 32, a pair of Velcro connector patches 80 are provided at each side of the harness with a patch sewn on each release strap 54, 54a and a complimentary patch attached to the ceiling of the wall extension 32.

The Y-strap link 56 for dropping the curtain when unwanted opening of door 40 occurs is constructed in an unbalanced arrangement of straps provided as a shorter and a longer arm 82, 820 that respectively, connect at their transverse directed ends to the main release straps 54, 54a and as a V converge into a shorter strap forming trunk 84. The arms 82, 820 are permanently sewed to their main release straps respectively at a lesser and a greater acute angle and the trunk 84, which is the apex or pulling point of the Y-strap link at component 34, is offset to one side of the vertical center line of door 40 which provides for equalizing or balancing the pulling of the strap link on the main release straps. Trunk 84 carries one member, e.g., a snap hook, of an attachable and detachable connector means 86 with the other member thereof, e.g., an eyelet or hasp, affixed near the top of the innerdirected face of the access door 40 and offset sidewise from the vertical centerline of the door to receive the snap hook member of connector means 86. The Y- strap link is thus easily attachable or detachable at will to the access door whenever it is desired to protect the building against loss of air through undesired opening of the door such as when the building is unattended.

It will be apparent from the foregoing and the drawing that with the curtain suspended and supported in the cradle, and the primary and secondary safety connection means of harness 52 operatively attaching the cradle to the frame and/or to the door those means can act as sensing means detecting relative movement occurring between portions of the building structure. Consequently if a break occurs in the connection between the auxiliary component 34 and the building extension 32 or between the latter and the main body of the building or in the event the door is opened when not desired, then sufficient relative movement between these portions of the structure causes the safety curtain apparatus to operate, opening or releasing the cradle and allowing curtain 22 to unroll over opening 30 and block any substantial outward flow of air therethrough.

Apparatus 20 and its curtain holding and releasing device 24 are usable in setting up and protecting the operation of the building generally as follows: The auxiliary component 34 with access door 40 closed is set up on the ground or other foundation in the desired position. The fabric of the building wall 28 with its connected wall extension 32 is laid out in deflated condition properly positioned adjacent the component. The outer end of the wall extension is then clamped to the auxiliary component with the curtain rolled down covering over opening 30 and the building then inflated. Where the wall extension is adapted to be releasably connected to the main body of the building the building can be set up and inflated with the curtain rolled down and secured to the wall 28 following which the extension, then attached to form part of the auxiliary component, can be connected to the building using any suitable fabric connector after which the curtain can be rolled up.

Following inflation, release straps 54, 54a are connected at their outer directed ends to the auxiliary component 34' using securement means 76 and their inner directed ends passed through the stirrups 66, 66a. The safety curtain is then manually rolled up from its bottom edge as indicated with support tapes 62, 62a and stirrup strips 64, 64a looped under it and the elements of disconnects 70, 70a connected together which suspends the curtain roll contained in its cradle above opening 30. Frictional holding by the stirrups under straps 54, 540 due to weight of the curtain assists to maintain the disconnects tensioned for secure holding together of the cradle and stressed to respond quickly when necessary to suflicient pulling by the harness to open the disconnects and release the curtain. The Y- strap link is left unsecured to the access door during periods of active building use when the door is in normal use.

In the event of wind storm or other event resulting in reduced pressure within the building such as when building inflating air must be supplied from auxiliary electrical equipment, extension 32 may pull with the main body of the building away from the auxiliary component, for example. In such events, with the main release straps 54, 540 and/or Y-strap link operatively connected between the cradle 50 and the respective parts of the auxiliary component, the main release straps will tighten and pull open the disconnects 70, 70a thus opening the cradle and allowing the safety curtain to unroll by gravity through guides of support tapes 62, 62a and the stirrup strips 64, 64a to cover the opening (See FIG. 7). When fully unrolled it can be seen that the curtain entirely covers the opening 30 and has its marginal edges overlapping the periphery of the opening and pressed against the inner wall surface of the building by the difference in air pressure within the building and the pressure external thereto (See FIG. 3).

When the building is left unattended the Y-strap link is connected at its otherwise free end at trunk 84 to door 40 by manual connection of the parts of connector means 86. Then, if the door is forced outward, main release straps 54, 54a are pulled by the Y-strap link to open the disconnects 70, 70a and release the safety curtain over opening 30 (See FIG. 8). Optimum positioning of the trunk 84 and the connector means 86 at door 40 for most effective pulling on the Y-strap link may vary with the particular installation. Also, arms 82, 820 can be made adjustable in length and angle of attachment to the main release straps to accommodate for variations in the size of an auxiliary component or of a wall extension thereto from the main body of the building structure.

It will be appreciated that the teachings herein may be applied to other types of auxiliary components such as sheds, or other types of pressurized or reduced pressure enclosures or the like where there is a requirement for security against unblocking of an air passage which would result in substantial unwanted air movement or the like therethrough. Also, the entire auxiliary component may at times be movable with respect to the main body of the building structure so as to partially or fully open the air passage thereinto, thereby triggering release of the curtain to block the opening or passage. It will further be appreciated that the safety apparatus herein can be arranged to be triggered by relative movement between the main chamber or body of a building and one or more auxiliary components or like structures or parts thereof such as access or closure doors or the like.

Moreover, the harness can have a fixed or adjustable length so the apparatus can be set to respond to a predetermined amount of movement between a portion of the main body of the building and the auxiliary component to effect the release of the curtain that immediately frees it to valve off the opening in the air passageway. Also, the harness may have disconnects at one end thereof in the form of breakaway members such as snap fasteners or the like for releasing said curtain or panel means.

Also, the structure can have a passageway positioned in it which frames or defines an opening into the building structure and that may be operatively continuously blocked by closure means during building use such as by a grille, glass panel or the like with a breakaway for holding and releasing the curtain having its releasing harness connection between the curtain and the closure means.

It will be appreciated that the invention may be embodied in other forms and that various modifications and changes may be made without departing from the spirit and scope of the inventive concepts presented herein.

What is claimed is:

1. A curtain device for automatically blocking a substantial loss of air from a passageway positioned in an inflatable structure comprising: a closeable passageway means positioned in said structure and defining an opening therein for allowing ingress to and egress from said structure; a movable curtain means releasably held for extension over said opening; and curtain releasing means automatically releasable in response to opening of said passageway means and operatively connected between said curtain means and said passageway means, whereby opening of said passageway means capable of causing a reduction in the inflation of said structure causes said curtain releasing means automatically to efi'ect the extension of said movable curtain means over said opening so as to block the exit of air therethrough.

2. The device of claim 1 in which said curtain releasing means includes a safety release means that is releasably connectable between said curtain means and said closeable passageway means, so that, when desired, it can be connected to effect a release of said curtain means when said passageway means is opened.

3. The device of claim 2 in which said safety release means is connectable to a door positioned in said closeable passageway means.

4. The device of claim 1 in which said curtain releasing means includes means for releasably holding said curtain means positioned so as to be extendable over said opening by gravity.

5. The device of claim 1 in which said curtain means is flexible and formed from a material that is resistant to the passage of air.

6. The device of claim 1 in which said curtain means is flexible and has a plurality of stiffening members therein which span the opening in said closeable passageway means.

7. The device of claim 4 in which said means for releasably holding said curtain means are breakaway straps.

8. The device of claim 7 in which said breakaway straps are maintained in curtain means holding position by snap fasteners.

9. The device of claim 1 in which said curtain releasing means is operative by the separation of said closeable passageway means from its connection to said inflatable structure that results in escapement of air from said structure.

10. The device of claim 9 in which said curtain device is detachable from said structure and said closeable passageway means.

11. A curtain device adapted to automatically block a substantial loss of air from a passageway positioned in an inflatable structure comprising: a movable curtain means adapted to be positioned adjacent to a closeable passageway means positioned in said inflatable structure that defines an opening therein for allowing ingress and egress to and from said structure, said curtain means extendable over said opening; and curtain releasing means automatically releasable in response to opening of said passageway means and operatively connectable between said curtain means and said passageway means, whereby opening of said passageway means, capable of causing a reduction in the inflation of said structure, automatically causes said curtain releasing means to effect an extension of said movable curtain means over said opening blocking the exit of air therethrough.

12. A curtain device for automatically blocking a substantial loss of air from a passageway positioned in an inflatable structure comprising: a passageway means positioned in said structure and defining an opening therein, a closure means positioned in the passageway means so as to block the opening against access into said structure, a movable curtain means releasably held for extension over said passageway means; and curtain releasing means automatically releasable in response to opening of said passageway means and operatively connected between said curtain means and said closure means, whereby opening of said passageway means capable of causing a reduction in the inflation of said structure causes said curtain releasing means automatically to effect the extension of said movable curtain means over said opening so as to block the exit of air therethrough.

l l i l 

1. A curtain device for automatically blocking a substantial loss of air from a passageway positioned in an inflatable structure comprising: a closeable passageway means positioned in said structure and defining an opening therein for allowing ingress to and egress from said structure; a movable curtain means releasably held for extension over said opening; and curtain releasing means automatically releasable in response to opening of said passageway means and operatively connected between said curtain means and said passageway means, whereby opening of said passageway means capable of causing a reduction in the inflation of said structure causes said curtain releasing means automatically to effect the extension of said movable curtain means over said opening so as to block the exit of air therethrough.
 2. The device of claim 1 in which said curtain releasing means includes a safety release means that is releasably connectable between said curtain means and said closeable passageway means, so that, when desired, it can be connected to effect a release of said curtain means when said passageway means is opened.
 3. The device of claim 2 in which said safety release means is connectable to a door positioned in said closeable passageway means.
 4. The device of claim 1 in which said curtain releasing means includes means for releasably holding said curtain means positioned so as to be extendable over said opening by gravity.
 5. The device of claim 1 in which said curtain means is flexible and formed from a material that is resistant to the passage of air.
 6. The device of claim 1 in which said curtain means is flexible and has a plurality of stiffening members therein which span the opening in said closeable passageway means.
 7. The device of claim 4 in which said means for releasably holding said curtain means are breakaway straps.
 8. The device of claim 7 in which said breakaway straps are maintained in curtain means holding position by snap fasteners.
 9. The device of claim 1 in which said curtain releasing means is operative by the separation of said closeable passageway means from its connection to said inflatable structure that results in escapement of air from said structure.
 10. The device of claim 9 in which said curtain device is detachable from said structure and said closeable passageway means.
 11. A curtain device adapted to automatically block a substantial loss of air from a passageway positioned in an inflatable structure comprising: a movable curtain means adapted to be positioned adjacent to a closeable passageway means positioned in said inflatable structure that defines an opening therein for allowing ingress and egress to and from said structure, said curtain means extendable over said opening; and curtain releasing means automatically releasable in response to opening of said passageway means and operatively connectable between said curtain means and said passageway means, whereby opening of said passageway means, capable of causing a reduction in the inflation of said structure, automatically causes said curtain releasing means to effect an extension of said movable curtain means over said opening blocking the exit of air therethrough.
 12. A curtain device for automatically blocking a substantial loss of air from a passageway positioned in an inflatable structure comprising: a passageway means positioned in said structure and defining an opening therein, a closure means positioned in the passageway means so as to block the opening against access into said structure, a movable curtain means releasably held for extension over said passageway means; and curtain releasing means automatically releasable in response to opening of said passageway means and operatively connected between said curtain means and said closure means, whereby opening of said passageway means capable of causing a reduction in the inflation of said structure causes said curtain releasing means automatically to effect the extension of said movable curtain means over said opening so as to block the exit of air therethrough. 